Predictions of Slat Noise from the 30P30N at High Angles of Attack using Zonal Hybrid RANS-LES

Housman, Jeffrey A.; Stich, Gerrit-Daniel; Kiris, Cetin C.

doi:10.2514/6.2019-2438

“…The hybrid RANS-LES model named the stress-blended eddy simulation, or SBES, introduced by Menter [22] is used in this work to provide closure to the Reynolds-averaged Navier-Stokes equations. The use of hybrid RANS-LES models in aerodynamic studies has previously been reported in the literature [23][24][25]. More recently, Syawitri el al.…”

Section: Turbulence Modelingmentioning

confidence: 99%

Near Stall Unsteady Flow Responses to Morphing Flap Deflections

Abdessemed

¹

,

Yao

²

,

Bouferrouk

³

2021

Fluids

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The unsteady flow characteristics and responses of an NACA 0012 airfoil fitted with a bio-inspired morphing trailing edge flap (TEF) at near-stall angles of attack (AoA) undergoing downward deflections are investigated at a Reynolds number of 0.62 × 106 near stall. An unsteady geometric parametrization and a dynamic meshing scheme are used to drive the morphing motion. The objective is to determine the susceptibility of near-stall flow to a morphing actuation and the viability of rapid downward flap deflection as a control mechanism, including its effect on transient forces and flow field unsteadiness. The dynamic flow responses to downward deflections are studied for a range of morphing frequencies (at a fixed large amplitude), using a high-fidelity, hybrid RANS-LES model. The time histories of the lift and drag coefficient responses exhibit a proportional relationship between the morphing frequency and the slope of response at which these quantities evolve. Interestingly, an overshoot in the drag coefficient is captured, even in quasi-static conditions, however this is not seen in the lift coefficient. Qualitative analysis confirms that an airfoil in near stall conditions is receptive to morphing TEF deflections, and that some similarities triggering the stall exist between downward morphing TEFs and rapid ramp-up type pitching motions.

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On the Flow Past a Three-Element Wing: Mean Flow and Turbulent Statistics

Montalà,

Lehmkuhl,

Rodriguez

2024

Flow Turbulence Combust

0

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Large eddy simulations (LES) on the flow past the 30P30N three-element high-lift wing at a moderate Reynolds number $$Re_c=750,000$$ R e c = 750 , 000 and three different angles of attack $$\alpha =5$$ α = 5 , 9 and $$23^\circ $$ 23 ∘ are conducted. The main focus is on the time-averaged statistics of the turbulent flow. The form drag noticeably increases with the angle of attack, while viscous drag remains roughly constant and contributes minimally to the total drag. This is associated with the significant pressure peaks found in the main element with increasing angles of attack and hence, the development of stronger adverse pressure gradients. At $$\alpha =23^\circ $$ α = 23 ∘ , this leads to the development of a prominent wake downstream this element that eventually evolves into a visible recirculation region above the flap, indicating the onset of stall conditions. In the flap, strong adverse pressure gradients are observed at small angles of attack instead, i.e., $$\alpha =5$$ α = 5 and $$9^\circ $$ 9 ∘ . This is attributed to the flap’s deflection angle with respect to the main wing, which causes a small separation of the boundary layer as the flow approaches the trailing edge. At the stall angle of attack, i.e., $$\alpha =23^\circ $$ α = 23 ∘ , the spread of the main element wake maintains attached the flow near the flap wall, thus mitigating the pressure gradient there and preventing the flow to undergo separation. The shear layers developed on the slat and main coves are also analysed, with the slat shear layer showing more prominence. In the slat, its size and intensity noticeably decrease with the angle of attack as the stagnation point moves towards the slat cusp. Conversely, the size of the shear layer developed in the main element cavity remains approximately constant regardless of the angle of attack. At the lower angles of attack, i.e., $$\alpha =5$$ α = 5 and $$9^\circ $$ 9 ∘ , the development of the shear layer is anticipated by the turbulent separation of the flow along the pressure side of the main wing, leading to increased levels of turbulence downstream. At the higher angle of attack, i.e., $$\alpha =23^\circ $$ α = 23 ∘ , the shear layer is originated by the cavity separation and transition to turbulence occurs within the cavity.

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Noise prediction research of a scaled turboprop aircraft

Song

¹

,

Song²,

Wang³

et al. 2021

西北工业大学学报

1

0

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Aerodynamic noise level has become an important performance index of civil aircraft, and it is drawing more and more attention. Most airframe noise research based on CFD method is aimed at aircraft individual parts at present, while lack of noise prediction for the complex high fidelity full aircraft model. Due to the interaction between aircraft parts, noise prediction between single part and the actual configuration are very different in the aspect of calculation conditions, noise generation and propagation. Only by using more realistic model can the noise be accurately predicted. In this paper, high-resolution mesh and high-precision hybrid RANS/LES method, combined with the FW-H acoustic analogy method, are employed to predict the noise of a turboprop's high-fidelity 1/6 scale model of landing configure. The improved delayed detached eddy simulation (IDDES) method was used to simulate the flow in the near-field sound source region, and the sound source characteristics of the whole turboprop are obtained. In addition to the two important noise sources-flap side edge and wing tip, numerical simulation also found other two important noise sources resulting from the interaction between parts-interaction between nacelle wake and flap, and the complex flow between flap inner side and fuselage. Results of far-field noise show that in the longitudinal symmetry plane of the fuselage, the noise mainly propagates to the lower front and over back direction, and the dipole characteristics are very obvious. In the plane perpendicular to the incoming flow, the noise in the transverse direction is weaker.

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Predictions of Slat Noise from the 30P30N at High Angles of Attack using Zonal Hybrid RANS-LES

Cited by 23 publications

References 50 publications

Near Stall Unsteady Flow Responses to Morphing Flap Deflections

Near Stall Unsteady Flow Responses to Morphing Flap Deflections

On the Flow Past a Three-Element Wing: Mean Flow and Turbulent Statistics

Noise prediction research of a scaled turboprop aircraft

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